The early earthquake warning system detects a P-wave (Primary Wave) of an earthquake, alerts the control center that there is an earthquake coming. Within seconds, the power of the overhead wire of the Shinkansen will be cutoff. Shinkansen relies current on the track to detect railway signals.

The Shinkansen (Bullet Train) in Japan is equipped with one of the most sophisticated early-warning systems in the world, known as UrEDAS (Urgent Earthquake Detection and Alarm System). When the first "P-waves" (preliminary tremors) are detected by sensors along the coast and the tracks, the system automatically cuts the power to the overhead lines and triggers the emergency brakes on all trains in the affected area—often before the more violent "S-waves" actually reach the tracks. This allows the train to decelerate significantly or come to a complete stop before the heavy shaking begins, drastically reducing the risk of derailment at high speeds. Since its inception in 1964, no passenger has ever been killed due to a Shinkansen derailment caused by an earthquake, despite Japan being one of the most seismically active regions on Earth. After the shaking stops, the tracks and overhead lines must be visually inspected for damage by maintenance crews before service can resume, which can lead to significant delays but ensures absolute safety.